CN1297085C

CN1297085C - Robust method and apparatus enabling multi-mode wireless optical communication

Info

Publication number: CN1297085C
Application number: CNB961995165A
Authority: CN
Inventors: 马丁·德·兰奇; 弗里茨·鲁道夫·格菲勒; 瓦尔特·赫特
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1996-01-03
Filing date: 1996-01-03
Publication date: 2007-01-24
Anticipated expiration: 2016-01-03
Also published as: CA2241937A1; EP0872049B1; WO1997025788A1; CN1207220A; HUP0001749A3; ES2193232T3; PL180350B1; EP0872049A1; DE69627886T2; ATE239332T1; HUP0001749A2; CA2241937C; DE69627886D1; US6442145B1; JPH11502096A; JP3202755B2; CZ204098A3; HK1016369A1; PL327574A1

Abstract

The present invention relates to an optical communication system for realizing the communication between a plurality of coexistent transmitting stations and receiving stations. The present invention adopts a robustness physical layer head (RPLH; 50) which can be comprehended by the stations which participate in communication, wherein the robustness physical layer head comprises a precedence code (52) which is composed of frames, and the frames are composed of a periodicity pulse sequence; the time slot numbers and the contents of each frame are known by the participating stations; the precedence code (52) is used for the corresponding synchronisation and carrier detect of the receiving stations. The RPLH also comprises a unique synchronous word (53), wherein the synchronous word (53) is used for the absolute synchronisation of the receiving stations; a control field (59) of the fixed length and the known structure is arranged behind the synchronous word (53), and a modulation method applied to the data transmission is known from the receiving stations. The control field (59) provides information, such as communication link, network control, etc., under some conditions. In addition, the information can be exchanged, and therefore, the data rate of transmission is conveniently negotiated and/or adapted. The present invention can optimize the throughput of the information according to the conditions (quality) of signal channels.

Description

Realize the robust method and the device of multi-mode wireless optical communication

Technical field

The present invention relates to the multi-mode wireless optical communication system, and work in the communication between the various kinds of equipment on the different mode and/or the communication of coexistence in this type of communication system.

Background technology

Along with the quick growth of work station and personal computer in all commercial fields, administrative organization and manufacturing sector (for example desk-top or portable) quantity, also require these systems to be coupled to each other flexibly and simply day by day.With regard to connecing of ancillary equipment hang and interconnected with regard to, similar demand is arranged, such as ancillary equipment such as keyboard, computer mouse, printer, plotter, facsimile machine, scanner, display and modulator-demodulators.Adopt electrical interconnection to become problem, and the position of system or the configuration of subsystem must often change in many cases along with the increase of the number of systems of intercommunication mutually.So, wish that this type systematic cancellation electrical interconnection is replaced employing wireless communication obtains flexibility.

In recent years, light signal is applied to the wireless transmission numerical data more receives publicity between system and the equipment, and in commercial product, obtains practicality.The light remote control of domestic electric appliance is exactly an example, and another example is the communication between the office environment internal information system.In the optical communication system, the numerical data that will transmit between transmitting system and the receiving system is transformed into modulated light signal earlier, it is by a light source in the transmitting system-particularly infrared (IR) radiation of light source is gone out, received by receiving system again, convert the signal of telecommunication to, then form numerical data.Light signal can directly be transmitted on the optical receiver in the receiving system, or can arrive on the optical receiver indirectly after the direction that change propagation through lip-deep reflection or scattering process.Today, the previous case has accomplished that in pocket computer and ancillary equipment the transfer of data there occurs between optical sender and the optical receiver, and the distance between them is very near, is 1～3 meter scope, can aim at exactly.Latter event typically is applied in the office environment, because direct path has inevitable disturbance, but the direct transmitting optical signal of interference-free is unpractical between the optical sender at some meters intervals and the optical receiver, or even impossible.A kind of known method that reaches high degree of flexibility is to make emission system with optical signal radiation to the ceiling of office or on the wall, and light signal is reflected or diffuse scattering there.Therefore, optical sender all around the radiation meeting in certain zone be interfered.Many factors are depended in the interference that the light signal that diffuses out from ceiling is subjected to, and they have characterized out the specific environment of being considered.Yet subject matter is transmission range in the content of being discussed, the distance between light emission system and the optical receiver system just, and it is limited to certain end value, after this is referred to as transmission range; This is because the emittance transmitted stream reduces along with the increase of propagation distance, and the sensitivity of optical receiver is subjected to the restriction of lowest signal-to-noise.Be operated in some the typical known systems on the luminous power grade, all be subjected to the restriction of light source performance, light-struck security requirement shows that transmission range is several meters under the 1Mbps data transfer rate.

The example in back shows the fundamental characteristics of understanding wireless light communication, and has pointed out its application scenario, there it than another kind of competitive wireless communications method that is radio frequency transmission method more favourable.Wireless light communication is allowed carry out transfer of data in short distance, and radio frequency transmission means long distance applications.In addition, because office's typical boundary of wall and ceiling and so on is opaque and one section of radio frequency is had transmission capacity to light, so the wireless light communication in the office environment is a locality.Therefore, in light radiation rather than wireless communication system, can more easily control the interference between the different communication systems, and can reach data security by simpler method based on radio frequency transmission.Radio frequency transmission also be subjected to the communicating by letter restriction of regulations and licence, and radio optical communication system does not have this kind restriction.

The critical performance parameters of radio optical communication system is the distance between the system of accessible data transfer rate and swap data.In office environment, may be at the enterprising row data communication of distance of the transmission range that surpasses single optical sender.But, in the category of wireless light communication, can extend the transmission range of single optical sender, for example extend by introducing optical repeater.An example of this kind stretch system is a United States Patent (USP) 4,402, and 090 is called " communication system of being transmitted data between terminal station and satellite station by infrared system ".In this patent, narrated a kind of system that a plurality of satellite stations are provided, these satellite stations are fixed on the ceiling of big room usually.In the transmission range of satellite station, optical communication can be carried out with them in the terminal station, and the communication between the station can distribute data via satellite, thereby the distance that data can be dispensed to outside the transmission range of single optical sender is last.

When the design radio optical communication system, people it should be noted that inevitable surround lighting, such as daylight or light, unless in the environment that the system that limits only is applied to deceive entirely, otherwise this lightlike line always arrives on the photodetector.Infrared energy in the surround lighting (fluorescent lamp, incandescent lamp, daylight) can cause the ripple of significantly making an uproar in the optical receiver.Therefore, surround lighting will influence the signal to noise ratio of optical receiver, thereby influence transmission range.The more detailed content of ambient light effects is published among PCT patent application PCT/EP 94,01196 October 26 nineteen ninety-five, debatable (publication No.WO95/28777).Presenting of surround lighting is statistical mostly, often is difficult to control, and its intensity can change significantly, because light can be connected/cut off, daylight also has change.Thereby influence to statistical the concrete effect that signal to noise ratio influences transmission range, will change along with the interrupted occurrence rate of receiver light signal on the light path.In office environment, the user who is for example walking about can make the intensity that sends signal change, and inevitably the influence of surround lighting also just changes.

In present light base wireless communication system, at first made great effort and come the processing environment optical issue.Usually, (≤500KHz) AC signal is to suppress them with electric filter after light signal converts the signal of telecommunication to for the low frequency that provides common room illumination.In addition, use the spectral component that optical filter limits unwanted surround lighting.Yet the major part of spectrum of sunlight is to be in the identical scope with the light radiation of the light source that is suitable for radio optical communication system.

As PCT patent application PCT/EP 94/01196 described above, and it is illustrated among another PCT patent application PCT/EP 94/00577 (publication No.WO 95/23461) of announcement on August 31 nineteen ninety-five, a kind of Infrared Wireless Communication system can be provided, it can overcome the basic problem in the commodity utility system effectively, such as incident surround lighting problem.Provided a kind of scheme in PCT/EP 94/01196, it can make and be used in surround lighting and have the radio optical communication system under the occasion of magnitude variations to reach dynamic optimization.

Developed the different schemes that is applied to wireless light communication, and carried out in specific occasions by the positive person of participating in.Various optical communication methods like this are incompatible.For example, the computer of first manufacturer production can not be connected on the printer of second manufacturer production by the wireless optical channel usually, because in most cases they work in the different patterns, optical sender/optical receiver hardware is incompatible.

Incompatible a part of reason be each other company be devoted to research and develop independently and irrelevantly cause.In addition, various uses of different nature requires different transmission plans (pattern), to reach sufficient data transfer rate and coverage distance.Exemplary has: be applied to directivity, High Data Rate desktop link on computer and the ancillary equipment, use the Local Area Network of the fixing or variable data rate of diffuse radiation, remote control system, low data rate paging function, and the link of such as cordless telephone, visiting wired based system and visit radio frequency system.Obviously, the characteristic of this type systematic is respectively at its purposes itself.

This means that the various optical communication packages of determining will inevitably coexist, just, people must tackle multi-mode system.Yet, expectation be, independent and irrelevantly be devoted to research and develop the difference that is caused and can pass in time and disappear, perhaps to stipulate a standard at least, make can intercom mutually between most systems.An example of this kind standard is existing IrDA standard.This standard is expanded in WKG working work, and detailed content is given in the article " with IrDA agreement infrared radio transfer files easily " of Bill Travis in the 17th to 22 page of July " electronics industry design magazine EDN " nineteen ninety-five.Also narrated the modulator approach of stipulating in the IrDA standard in the article.

Also do not have at present a kind of desirable solution, it be adapted to current and light base communication system in the future in different requirement and needs, and they can coexist and/or compatibility to guarantee in common operation environment (for example in a large-area office).

Therefore, an object of the present invention is to provide a kind of radio optical communication system, it can accomplish multi-mode working.

Another object of the present invention provides a kind of method and apparatus, is applied to wireless multi-mode formula optical communication system.

A further object of the present invention is to solve typical problem in the existing optical communication system, that is problems such as channel quality assessment and frame/sign synchronization.

Another purpose of the present invention provides a kind of method and apparatus, even can be applicable to the wireless multi-mode formula optical communication system of working under the channel condition of extreme difference.

Summary of the invention

The present invention who proposes the patent requirement is with being intended to satisfy these purposes.It provides the method and apparatus that can carry out wireless light communication between a dispatching station and first receiving station and second receiving station, first receiving station can receive the data of using the modulation of first modulator approach, and second receiving station can receive the data of using the modulation of second modulator approach.For this purpose, use a kind of novelty, creationary healthy and strong physical layer header (RPLH).According to the present invention:

1. described dispatching station provides a preamble, and it comprises some frames that formation one-period pulse train also promptly has the pulse train in definite cycle, and number of time slot (L) and content frame in every frame are that described receiving station will know;

2. described dispatching station launches described pulse train with the form of light;

3. each of described receiving station is carried out carrier wave according to the described pulse train that receives and is detected;

4. each of described receiving station is determined the cycle of described pulse train, and is synchronous relatively to obtain;

5. each of described receiving station is adjusted its clock, on the time slot phase place of the pulse train that receives, and the described input pulse sequence by shift register is set clock with phasing;

6. the synchronization character of a uniqueness of described dispatching station emission, it was calibrated on the cycle of described preamble;

7. each of described receiving station is asked correlation to the known described unique synchronization character of the described pulse train in the described shift register and receiver, so that reach absolute synchronization with described dispatching station after identifying described synchronization character;

8. described dispatching station points out in the control field of predetermined length now, in additional data/subsystem field, will use which kind of modulator approach, so that can support described whole receiving stations of relevant modulator approach waiting in these data/subsystem field with the data of transmitting.

It is not enforceable in proper order to it may be noted that top step, and some step also can be implemented with parallel mode.

The invention provides a kind of method that between dispatching station and first receiving station and second receiving station, realizes wireless light communication, first receiving station can receive the data of using the modulation of first modulator approach, second receiving station can receive the data of using the modulation of second modulator approach, and this wireless light communication method is characterised in that:

A. described dispatching station provides a preamble, and it comprises all Frames that form the one-period pulse train with definite cycle, and the content of the number of time slot and frame is that described all receiving stations are known in every frame;

B. described dispatching station transfers out described pulse train with the light signal form;

C. described all receiving stations carry out carrier wave according to the described pulse train that receives and detect;

D. each of described all receiving stations is determined the cycle of described pulse train, and is synchronous relatively to obtain;

E. each of described all receiving stations is adjusted to its clock on the time slot phase place of the pulse train that receives, and sets the clock of the pulse train of described input by shift register;

F. described dispatching station transfers out a synchronization character of calibrating the uniqueness on the described cycle, and the synchronization character of described uniqueness is that described all receiving stations are known;

G. each of described all receiving stations is asked correlation to the synchronization character of the known described uniqueness of the described pulse train in the described shift register and receiving station, so that receiving station reaches the absolute synchronization with described dispatching station behind the described synchronization character of identification;

H. described dispatching station indicates in the control field of predetermined length and structure, is that first or second modulator approach will be used to transmit the data in data/subsystem field, makes to support whole receiving stations of relevant modulator approach all waiting for described data.

The invention provides a kind of transmitter that is used for carrying out wireless light communication with first receiving station and second receiving station, first receiving station can receive the data of using the modulation of first modulator approach, second receiving station can receive the data of using the modulation of second modulator approach, energy of described optical communication applications is started by the healthy and strong physical layer header of all receiving station's decodings, and described transmitter comprises:

A., a head generator of preamble is provided, described preamble is as the part of described healthy and strong physical layer header, comprise all frames that form the one-period pulse train with definite cycle, the number of time slot of every frame and the content of frame are that described all receiving stations are known;

B. be used to provide the device of the synchronization character of the uniqueness of knowing as a part and described all receiving stations of described healthy and strong physical layer header;

C. be used to provide have regular length and known structure, as the device of the control field of the part of described healthy and strong physical layer header, described control field indication in transfer of data with the relevant modulator approach that adopts;

D. make the described data that to transmit realize the device of modulation; And

E. the device that will be subsequently transmits in the described pulse train of the synchronization character of the described uniqueness of described preamble, synchronization character is calibrated on described pulse train, described control field and described modulated data.

Be used for carrying out in multi-modal communications network element and a dispatching station receiver of wireless light communication, described dispatching station transfers out:

A healthy and strong physical layer header, it can be by all receiver decodings in the described multi-modal communications network element, and it includes:

Preamble, it comprises all frames of forming the one-period pulse train with definite cycle, the number of time slot of every frame and the content of frame are that described receiver is known;

The synchronization character of the uniqueness that described receiver is known;

A control field with regular length and known structure, it indicates in the transfer of data the relevant modulator approach that adopts;

Described receiver comprises:

A. the content of number of time slot in every frame of knowing according to receiver and frame is determined the cycle of described pulse train so that obtain relative synchronous device;

B. carry out the device that carrier wave detects according to described pulse train;

C. the clock of receiver is adjusted to the device on the phase place of crack in the described pulse train that receives;

D. the described pulse train that receives by a shift register is determined the device of clock, the length of shift register is determined by the synchronization character of described uniqueness;

E. the synchronization character of the known described uniqueness of the described pulse train in the described shift register and receiver is asked correlation so that receiver reaches the device of absolute synchronization with described dispatching station after identifying the synchronization character of described uniqueness;

F. determine the device whether described receiver can support relevant modulator approach from described control field, this modulator approach will adopt in described transfer of data;

Whether g. determine described receiver from the information that receives is the device of the proper reciever of described data; And

The device that receiver is received the described data of the tight back of described control field.

The present invention also provides a kind of multi-mode wireless optical communication system, comprising: at least one transmitter, and this transmitter comprises:

A head generator of preamble is provided, described preamble is as the part of described healthy and strong physical layer header, comprise all frames that form the one-period pulse train with definite cycle, the number of time slot of every frame and the content of frame are that described all receiving stations are known;

Be used to provide the device of the synchronization character of the uniqueness of knowing as a part and described all receiving stations of described healthy and strong physical layer header;

Be used to provide have regular length and known structure, as the device of the control field of the part of described healthy and strong physical layer header, described control field indication in transfer of data with the relevant modulator approach that adopts;

Make the described data that to transmit realize the device of modulation; And

With the device that transmit with the described pulse train of the synchronization character that described uniqueness is arranged the back, synchronization character is calibrated on described pulse train, described control field and described modulated data; With at least one receiver, this receiver comprises:

The number of time slot in every frame of knowing according to receiver and the content of frame are determined the cycle of described pulse train so that obtain relative synchronous device;

Carry out the device that carrier wave detects according to described pulse train;

The clock of receiver is adjusted to the device on the phase place of crack in the described pulse train that receives;

The described pulse train that receives by a shift register is determined the device of clock, and the length of shift register is determined by the synchronization character of described uniqueness;

Synchronization character to the known described uniqueness of the described pulse train in the described shift register and receiver is asked correlation so that receiver reaches the device of absolute synchronization with described dispatching station after identifying the synchronization character of described uniqueness;

Determine described receiver and whether can support the device of relevant modulator approach from described control field, this modulator approach will adopt in described transfer of data;

Whether determine described receiver from the information that receives is the device of the proper reciever of described data; And

Depend on concrete implementation method, if dispatching station further indicates the length of additional data/subsystem field in described control field, make receiving station can extract described information to determine the silent time span of itself transmitter, avoided with the transmission of carrying out (actual carrier detects) signal collision taking place by it, this will be favourable.Under some situation, it is also very useful also to provide other control information to be used in communication link and the network control in described control field.In addition, can exchange message so that consult and/or adapt to the data transfer rate of using in the transmission.This can make the throughput optimization that depends on channel condition (quality).It also helps providing the priority visit information, and will allow has the coexistence of experimental process network element in the same communication network element.

Further advantage of the present invention and use the additional examples that creationary healthy and strong physical layer header can carry out information exchange is below being described in more detail in.

The present invention can or be applied to the intrasystem communication of monotype, also promptly in the communication of supporting to carry out between the station of same modulator approach, or is applied to communication in the multi-mode system.In order to ensure carrying out multi-modal communications, must provide according to relevant hardware of the present invention, and must start any communication according to top step.

Description of drawings

Below, describe the present invention in detail with reference to following accompanying drawing:

Fig. 1 lists a table, shows the selection of understanding that infrared subsystem (S1-S4) different, coexistence and typical case use.

Fig. 2 illustrates the receiver example according to a multi-mode receiving station of the present invention, is operated in subsystem S1, S2 and the S3.

Fig. 3 is the generalized schematic at the multi-mode station of communicating by letter in a communication network element according to the present invention.

Fig. 4 A illustrates a pack arrangement that has healthy and strong physical layer header according to the present invention.

Fig. 4 B illustrates the control field example according to healthy and strong physical layer header of the present invention, and the modulator approach example in data/subsystem field (the intrasystem 4-PPM of S1).

Fig. 5 illustrates the general block diagram according to monotype radio optical communication system of the present invention.

Fig. 6 illustrates the general block diagram according to a self-adapting data rate of the present invention (variable data rate) system, has specifically shown the functional block that is used for channel quality assessment and frame/sign synchronization (identification synchronously).

Fig. 7 illustrates for data transfer rate compression (RR)=1,2,4,8 system, the state transitions reduced graph of major state equipment among Fig. 6.

Fig. 8 illustrates CSMA/CA (carrier wave that can avoid colliding the detects multiple access) agreement of combined standard, according to data transfer rate recognition mechanism of the present invention.

Fig. 9 illustrates the example according to data transfer rate connection table set of the present invention.

Figure 10 illustrates the user network information that derives from the data transfer rate connection table of Fig. 9.

Figure 11 illustrates the general block diagram according to receiving station's part of the present invention, is used for frame/sign synchronization (123 parts of Figure 12).

Figure 12 illustrates the general block diagram according to the present invention's a receiver part.

Figure 13 illustrates for passing through RR _MaxAnd adopting RR=1,2,4,8 system comprises the state transitions reduced graph of the receiver of Figure 12 function.

Figure 14 is the overview example of the synchronization character used of the 4-PPM according to the present invention, and it is used two synchronization characters and forms.

Embodiment

Generally, be applied to comprise at least in the system of wireless light communication a station and a station as optical receiver as optical sender.A light source is arranged in the transmitter, and for example a light-emitting diode (LED) or a laser diode have a photodiode in the receiver.After this, noun " is stood " as the synonym of computer, terminal, transponder and the ancillary equipment etc. of all kinds, and they can be communicated by letter each other.The present invention also can be applicable to communicate in the monotype communication system, but should be pointed out that the present invention is particularly suitable for the communication in multi-mode system.

Usually, infrared light is applied in the wireless light communication, and term " infrared communication " often uses below, and the present invention who is proposed is not restricted on the particular range of spectrum.

1) creationary healthy and strong head

A kind of creationary head (will illustrate in more detail in the back) is proposed below, it is very reliable on detecting, even also can be by all receiver identification and decodings of being in the same communication network element (for example office space) under the condition that normal communication no longer may be carried out.In addition, creationary healthy and strong head can make to be co-located between the difference station in the same communication network element realizes communication, also promptly can realize, coordinates and support communicating by letter wherein working between the station of different mode.Comprise a preamble in the creationary healthy and strong head, be used for that timing in receiving station is obtained, carrier wave detects with relative synchronous.The synchronizing sequence that also comprises a uniqueness in the healthy and strong head to the identification of synchronizing sequence, can be guaranteed the absolute synchronization between transmitter and receiver in the dependence receiver.In addition, also comprise a regular length control field that after synchronization character, then sends.This control field is used for providing about user data rate information, data block size information, modulator approach information that support and/or expectation to receiving station, and other relevant (7) system information.Especially, it comprises such information again, in order to identify the data of following after healthy and strong head or recipient's (addressee's form) of information.

2) compatibility/coexistence of different transmission meanss

At present, the signal that is sent with certain pattern (for example subsystem S1 among Fig. 1) by the transceiver of a dispatching station in multi-mode system can not be received and understanding by the receiver of any receiving element another pattern (for example subsystem S2 among Fig. 1) under; Vice versa.

Below, will further describe novel healthy and strong head in detail, it is also referred to as healthy and strong physical layer header (RPLH), and design overcomes the incompatibility between symbiotic system.In addition, will the structure of RPLH, the method to its application imagination, corresponding transmitter and receiver and the multi-mode wireless optical communication system that forms be described.

Importantly, if send a packet or controlling packet, each station that participates in communication in a communication network element will send a RPLH.According to showing bright concrete application in the table that provides among Fig. 1, each station in this communication network element belongs to forms subsystem (S _x) a station set.Participate in subsystem communication more than one type if dispose a station, then it will be a part of all corresponding subsystems.According to the present invention, an example of multi-mode receiver 35 roughly is illustrated among Fig. 2 in the station of support subsystem S1, S2 and S3.It comprises the amplifier 30 and the photodiode 36 of a part of forming AFE (analog front end), and three band pass filter 31-33, and they for example are used for leaching each other signal that receives via optical communication channel 14.Filter 31 (WBW) is used for extracting the signal that is applied to subsystem S2 communication, and filter 32 (VBW) is applied to subsystem S1 communication, and filter 33 (SBW) is applied to subsystem S3 communication.The output of these filters 31-33 can be connected on the digital processing element 34.

Station 41 (A) among Fig. 3 for example belongs to subsystem S1 and S2, and S1 is made up of

station

41,42,43,44,46 (A, B, C, D, F) here, and S2 is made up of station 41 and 42 (A and B).A station also can be provided for the repeater function degree of some subsystem.Station 46 (F) among Fig. 3 for example only is provided for the repeater function of S1, and is specified as SIR, and stand 42 (B) in being operated in S1, S2 and S3 as the terminal, be provided for the repeater function (SIR) of S1 again.The scale of communication network element 40 is decided by to participate in the accessible maximum transmission distance of subsystem of communicating by letter the most healthy and the stronglyest.Usually, it is the subsystem with lowest data rate work, for example provides the subsystem S4 of paging function.

Creationary healthy and strong head (RPLH) 50 is shown in Fig. 4 A.The so-called actual carrier that RPLH50 has based on channel retention time mode detects (VCS) mechanism.At least comprise preamble field 52 and synchronization character field 53 in the creationary healthy and strong head 50, they deliver preamble and synchronization character respectively.In addition, it also comprises the control field 59 of predetermined length.Can comprise the information of supporting self adaptation (variable) data rate systems in this control field 59, there is explanation this aspect in the debatable PCT patent application PCT/EP 94/01196 that announces October 26 nineteen ninety-five.The back will further provide the field details of healthy and strong head 50.

The network that all stations that participate in the RPLH base (multi mode terminal and transponder) constitute is subjected to the control at each station of comprising in the subsystem of the highest networking capacity.This station set is called monitor network (SN).Among Fig. 3, SN is made up of

station

41,42,43,44 and 46 (A, B, C, D and F), also is that the variable data rate network is as the SN in this example.Must dispose a receiver front end at least based on each station in the communication network element (it will participate in wireless light communication) of RPLH, it can receive and understand by the RPLH in the employed modulation system in all stations of forming SN.

According to the present invention, RPLH transmission is divided into two stages basically and realizes.

The front end that each station in the stage 1:RPLH scope (communication network element 40) has is activated to receive healthy and strong head.Hope sends a station of data and waits by the time the SN channel is in idle condition, so it sends out RPLH, wherein preferentially comprises the information of VCS and pattern aspect.This message is all listened at other station in the described communication network element, and handles the information that is transmitted.If indicate a kind of modulator approach in the control field 59 of described healthy and strong head, which station can be supported, then should store VCS information down in the station, and keep working during the stage 2.Otherwise it can set it time is up counter according to the VCS information that receives, and enters such as battery saving mode.VCS information also is the retention time of wireless channel aspect, is the data transfer rate that is indicated by dispatching station from control field 59 transmission, derives in data block size and the pattern information.

Stage 2: the receiving station that maintenance is worked switches to their receiver front end on the pattern that indicates in the received control field 59, and determine whether point to them to judge this message for stay of two nights address that send, that received in the described control field 59.All stations of selected address all do not enter such as battery saving mode, and etc. by the time finish until the channel retention time.By the station of addressing now can and the starting station (dispatching station) between under its proprietary pattern, communicate, condition is that channel is being retained.

As described above, the design's thought has accomplished that not only all receivers have reliable carrier wave to detect in the communication network element, the receiver that comprises those predetermined lowest signal-to-noise (SNR), and notified channel that the data block that is sent out is taken information how long to them.This principle is called actual carrier and detects (VCS), and it is used and optimizes, and makes that it can be in conjunction with in the healthy and strong head design thought that is applied to here.

3) be used for the healthy and strong head of pulse position modulation (PPM) system

Utilize example to further specify the details of healthy and strong head.

The transformat of RPLH50 must be deferred to the modulator approach of SN among Fig. 4 A.For each station of the communication network element that is designed to participate in the RPLH base, RPLH50 must be decoded.Healthy and strong head also should help to alleviate so-called concealment terminal problem.Just, stipulate out the structure of healthy and strong head, which part is deferred to the modulator approach of relevant SN, which the part be suitable for being operated in addition very disadvantageous condition under, promptly Na Li SN (for example SN=S1) itself becomes and can not carry out exchanges data work, and some subsystem (for example paging function subsystem of low data rate) but keeping operating state.

The exemplary embodiment of creationary healthy and strong head:

For the variable data rate system, PPM is the modulation system with peak efficiency.So, the structure of the RPLH that the system based on PPM uses, related particular problem are described here, and the solution of suggestion.The details of suitable control field 59 is shown on Fig. 4 B.Suppose in the following narration, communication system (also is the 4-PPM symbol based on a kind of specific PPM data symbol form, two information bits of each symbol delivery), yet, rely on suitable adjustment, the method is effective comparably in the system that uses different data symbol form (for example L-PPM symbol, every symbol delivery log2L information bit).

In the present embodiment,, provided various piece, coding method and the transmission symbol number of healthy and strong header fields 50 for a variable data rate system based on the 4-PPM sign form.The S1 subsystem plays SN among Fig. 1:

1. preamble 52:

Preamble 52 makes and is used for obtaining the synchronous relatively of receiver.In order to reach this point, send out preamble 52, it is the pulse train of one-period.Receiving station knows in each Frame to comprise how many time slots, after a moment later, just can detect the cycle of described pulse train.In addition, receiving station's applied clock restore circuit (phase-locked loop PLL) is adjusted its time slot clock phase (clock recovery).The pulse train that can realize as quickly as possible that the time slot clock phase is adjusted is adopted in suggestion.For this reason, suggestion pulse train is 10001000... or 10000010..., its each all can be applicable in 16-PPM and two kinds of forms of 4-PPM.Adopt different pulse train also can rely on preamble to carry out simply (control) message transmission separately.

2. synchronization character 53:

Can comprise an encoded binary sequence (for example sequence of 32 bits) in the synchronization character 53, it has optionally autocorrelation and and 52 low cross correlations of preamble sequence.In this example, each bit is mapped to 4 time slots, with the duty cycle of preservation as preamble sequence 52: if this bit is " 1 ", a pulse takes place in first time slot of 4-PPM symbol; If this bit is " 0 ", then pulse is arranged in the 3rd time slot.Impossible bit combination of searching for these two kinds of time slots at reception period is to improve Synchronous Processing (for example correlation) result.Further details will describe in conjunction with Fig. 6 and Fig. 7.Another synchronization character of being made up of the synchronization character of two separation is shown in Figure 14.

(3.RR data transfer rate compression) 54:

Under the situation of application of repetition coded, RR field 54 is a word (for example 4 bits) in subsystem, and it comprises the data transfer rate compression parameters RR of data/subsystem field 51 (field that also promptly comprises data) Shen subsequently.The data transfer rate compression parameters indicates, and how each pulse position modulation (PPM) symbol repeats frequently in data/subsystem field 51.

For other subsystem, it is such as playing the data transfer rate designator.In having the 4-PPM form of repeated encoding, RR field 54 is transmitted by 2 characters.

4.RR ^*(the data transfer rate compression of suggestion) 55:

RR ^*Field is a word (for example 4 bits), and it is included in the data transfer rate bulkfactor RR that receives during the last data block (being used for the channel quality assessment that subsystem is supported) from the suggestion of channel quality (error rate) derivation of assessment ^*It can be encoded by the same mode of RR.

(5.BS data block size) 56:

Be included in data/subsystem field 51 number in the data block size son field 56 with the data cell of transmission.In order to reduce expense, people can only stipulate a limited number of various data block size; For example, can distinguish out 16 kinds of different data block sizes with the corresponding mapping of 4 bits.Data block size son field 56 can be encoded by the same mode of RR symbol.

6. pattern 57:

Mode subfield 57 notice receivers, the modulator approach of the data that will transmit in data/subsystem field 51 is how, and whether data/subsystem field 51 should pass on by a transponder again.The number of mode bit is selected enough greatly, so that can hold subsystem in the future.This symbol can be encoded by the same mode of RR symbol.

Information transmitted can be used to determine in RR field 54 and BS field 56, in data/subsystem field 51 how long will there be the transmission of data.For the receiving station in addressee's form not, this information is important, because they need know that optical channel also is that how long silent they will keep with how long occupied.

In order to make the minimum that influences of direct current (DC) or low frequency component, the AFE (analog front end) of infrared receiving set is usually designed to and is used for exchanging (AC) coupling operating state.Therefore, the symbol that is changing duty cycle will require expensive (analog) DC restoration circuit.In addition, the selection of the pulse amplitude of transmitter and symbol duty cycle must be according to influential average power of infrared light supply and peak power are retrained; The latter is present in the light-emitting diode (LED) or laser diode that forms of radiation is arranged in the infrared light frequency spectrum usually.

Suggestion has the duty cycle identical with the 4-PPM data symbol, to defer to power constraint as applied pulse composition in one of RPLH the example.Same duty cycle also can realize in synchronization field 53, rather than resembles and use different duty cycle the common practices.During RPLH that employing proposes above, an additional benefit is need not use DC restoration circuit.If the direct current offset that forms to a certain degree, when consequently compensation is considered to essential, then can be used the method for controlling threshold value that Figure 12 middle finger goes out to performance impact.

Depend on used transmission means, can use a kind of algorithm and determine channel quality, the feasible data transfer rate that can draw maximum possible.Because all receiving stations of working in communication network element, the beginning of data/subsystem field known definitely, so by analyze the data that receive from data/subsystem field 51, these receiving stations can determine channel quality.Can demonstrate maximum data rate possible in communication network element and about the out of Memory of state, so that inform that the user is such as transmitting data under what kind of speed.

According to the present invention, if other communication means lost efficacy in a multi-modal communications network element, healthy and strong head can be used for exchange message between some stations of determining.In the case, though some information still can be transmitted, throughput is very limited.

Under some situation, send out privilege of access information and benefit in control field 59, it is suitable for the information of the communication network element of the information of first communication network element and second interference is differentiated.A kind of like this way can make the different communicator network element that works simultaneously be co-located in the single communication network element 40, and each subnet unit can require whole channel capacity, needn't take the actual carrier that is comprised among the next RPLH of other subnet unit into account and detect information.The reason that can accomplish this point is that the signal strength signal intensity in this seed network element is sufficiently high, can be caught by channel, is not subjected to the damage of the first interference of other remote subnet.Can comprise two or more mobile radio stations or fixed station in the communicator network element, and can comprise a station and be used to connect cable network (LAN).

Fig. 5 illustrates first implementation method of the present invention.According to this implementation method, if will send out Payload (binary data) or information, just produce RPLH by optical channel 14.RPLH is produced by head generator 10, and binary data is handled by a suitable encoder 11 and encoded, and it is used for binary data is mapped to the PPM symbol.In addition, also can use Forward Error Correction (FEC) system (not shown).

In this first implementation method, encoder adopts a pulse position modulation (PPM) encoder 11.Light-emitting diode (LED) exciter 12 is fed to signal waiting for transmission on the LED17.The fan-out amount of LED exciter 12 can be up to 8 equipment, and the peak value complex light power ratio of generation is as reaching 2 watts.At the other end of optical channel 14, there is a photodiode 18 (perhaps photodiode array) to receive the signal that LED17 comes.The output of photodiode 18 is handled by the AFE (analog front end) 13 of receiver, for example comprises an amplifier and automatic gain control (AGC) circuit in the AFE (analog front end) 13.Best, AFE (analog front end) 13 should be designed to prevent that from there is the locking that causes in the surround lighting because of high-magnitude, and agc circuit must provide 70dB above great dynamic range.Do not adopt soft demodulation method to avoid the complexity of many bit process, be added on the threshold circuit 15 (comparator) and provide the analog signal of controlling with amplitude by AFE (analog front end) in the present embodiment 13, it produces a binary output signal continuous in time.Then, this output signal is handled by digital processing element 16.Unit 16 comprises such function at least: carrier wave detects (carrier wave detection), and slot timing recovers, and analyzes the relative and absolute data sign synchronization after the field 52 and 53 among the RPLH.Depend on information transmitted in the control field 59 of RPLH, also configurable extraction, data decode and channel quality assessment in the digital processing element 16 with user data rate and data block size information.Digital processing element 16 example is provided in conjunction with Fig. 6 and is illustrated in the receiver.

Among Fig. 6, show an embodiment details of digital processing element 16 in the receiver.After from comparator 15, receiving the preamble Frame, at first by having variable loop gain and pretreated single order DPLL digital phase-locked loop (PLL) 60 recovers the time slot clock, so that tackle the PPM signal of the ripple of making an uproar preferably.By the time slot sampler 61 that the binary signal that threshold circuit 15 is sent is processed, cross sampling according to n times (for example n=8) and carry out phase estimation and phase place adjustment subsequently.The PLL loop gain is controlled by major state equipment 63 (MSM), and the work of MSM63 is shown among Fig. 7.Best, higher initially gain setting being got of receiving of preamble, obtain to obtain fast phase place, and reduce the uncertain possibility of PLL60 state.During phase place to the received signal keeps following the tracks of,,, after carrier wave and preamble data being made correct detection, loop gain is changed on the lower value by the carrier wave checking circuit according to this implementation method in order to prevent the slippage of local clock phase place.PLL60 is locked on the rising edge of input signal, and the time slot clock of recovery (for example 4MHz) is fully delayed time, the time slot sampler is played the effect of benchmark.For the time slot sampling that does not have performance degradation, 45 ° sampling clock phase resolution is enough.The time slot clock of the remainder of circuit and recovery (for example 4MHz) locking time.Sign synchronization realizes in two steps.The sequence of incident is comply with the reduced state diagram of the MSM63 shown in Fig. 7.After carrier wave detected, a carrier wave checking circuit was searched suitable preamble composition, and when searching out the effective pulse train of preamble 52, notified MSM63.Back, MSM63 by a triggering signal of calibrating with preamble phase place (position of preamble pulse) is provided, starts Symbol Synchronization Circuit in the synchronous identification frame 62 according to first time slot in the synchronization character of special coding.From at this moment, as the vertical sync circuit of synchronous identification frame 62 parts the information stores that finds in 32 symbolic frames is in succession gone in one the 32 bit shift register in the synchronous identification frame 62, its output is presented in the correlator and (be it may be noted that the supposition synchronization character is 32 bits in this example).The further details of recognition unit 62 is given on Figure 11 synchronously.If the known sequence of the pulse train that searches out, be fed into shift register after receiving and receiver is identical, then can reach absolute synchronization, also be that MSM63 thinks, the beginning of the control field 59 of regular length is just just found in the front of PPM coded data piece.To reach absolute synchronization in order indicating, on the output line 67 of discerning frame 62 synchronously, to provide a synchronous Q-character information.

Similarly, people also can use a kind of algorithm and suitable synchronization character 53, even the synchronization character that receives is partly damaged, this synchronization character 53 still can absolute synchronization.An example of this kind synchronization character is given in Figure 14, and suitable receiver hardware is shown in Figure 11.For example, if having the result of calculation in each of lock-out pulse symbolic frame cycle to show for expecting, the output of comparator 112 surpasses certain threshold value Ths (seeing square frame 113), and then MSM63 can think the beginning of having found control field 59.Like this, synchronization character also can deliver the additional information that will determine the address in the back.

If found the beginning of the control field 59 of regular length, just also known the beginning of data/subsystem field 51.According to the present invention, all data/subsystem field 51 is the place of PPM coding, all subsequently symbol thereby all be interpreted as the PPM symbol.Each field 54-57 as shown in Fig. 4 B, in pulse accumulator 64 with add up frame by frame (for example being 16 times), and by suitable symbol estimation circuit 65 valuations.For the Data Detection in data/subsystem field 51, can use same program according to the RR information that receives in the control field 59.It is contemplated that out diverse ways, how the information of delivery can decode and transmit in the control field 59, and receiver must be made corresponding design thereupon.

If whole data/subsystem field 51 correctly receives, can produce a triggering signal and be used for increasing informatio throughput measuring circuit, and the packet success rate counter reset.

The error rate on 66 pairs of infrared channel 14 of channel quality assessment device is monitored.In this implementation method, use the reason of digital channel quality assessment device 66 to be, rely on the SNR of analog circuit to determine or the surveying work of packet success rate, expensive, or speed is slow, therefore all not really suitable.The error rate of channel quality assessment device 66 monitoring infrared channel 14.From the error rate that this is assessed out, can determine data transfer rate bulkfactor (RR about suggestion in data/subsystem field 51 in the future ^*).Make quick feedback response aspect for transmitter in the cell site, the transmission error code counting can be finished on the PPM symbol level rather than on data/subsystem field level.Obviously, the PPM symbol of mistake (being 0,2 of every frame, the 3...... pulse) is counted by investigating each symbol that receives severally.Then, with the ratio of the total number of symbols that receives in error code symbol and data/subsystem field 51 of investigating, measure as of the instantaneous error rate on the infrared channel 14.

Below, provide a scheme example of data transfer rate negotiation aspect.The maximum possible data rate that reaches no error code ground bag transmission (wrapping on the medium access control protocol level of error code repeats) in fact can change in wide scope in a short time.Their present suitable data rates need be intercoursed in those stations that can be adaptive to their data transfer rate.In order to prevent the transmission again of repetition, this exchange of data rate information can realize in the error code feedback message.

According to the data transfer rate machinery of consultation that proposes, according to the Frame that receives at last in the respective field of RPLH, each station sends out the data transfer rate compression (RR of suggestion ^*) parameter.Show brightly among Fig. 8, use " request sends/dispose transmission " and (RTS/CTS), in a CSMA/CA (carrier wave detects multiple access/collision and avoids) agreement, how to realize the data transfer rate negotiation procedure.The data transfer rate that is proposed consults to be based on following principle:

According to all data that receive and control frame (total number of its L-PPM symbol surpasses 128) channel quality is made assessment.

The data transfer rate of data transfer rate, especially control frame, the unwanted again transmission of self adaptation conservatively to prevent to cause by impaired CTS frame or affirmation (ACK) frame.When bumping and when the channel signal to noise ratio snr is high, transmission is suitable again.Under the low situation of channel SNR, coding (promptly increasing RR) is comparatively effective repeatedly.

Introduce the data transfer rate compressed symbolic of an enforceable ACK frame, and guarantee only to need again transmission data block once with the transmission suggestion.

Detect problem in order to alleviate carrier wave, can adopt a kind of network allocation method (being similar among the IEEE 802.11).Reservation information should be transmitted with the redundancy of maximum possible.For adaptive data rate transmission system, propose to rely on the data transfer rate compression (RR) of transmission in the control field 59 and the channel retention time that data block size (BS) is calculated reality.

Take place below netinit in the communication network element (for example referring to Fig. 3) can resemble: by sending out a special control frame to each subsystem regulation, a station with S1 capacity starts network and brings into operation.This situation at first betides S1, and wait for to obtaining the response that all other S1 stations are come at the station of this startup then.Carry out in an identical manner to S2 and S3 at the station that starts.Finish after this, carry out in the same way according to selected channel access protocols at all other stations, and its relevant subsystem is distinctly carried out.At last, all station connection form that their are confirmed transfers to each station on their forms.Rely on this method, each station obtains the state diagram that every kind may connect in the network, comprises initial channel quality information.After this these state diagrams are called data transfer rate/connectivity state figure.According to this information, can identify the concealment terminal in the communication network element.In addition, during netinit, also can transfer out concerning it is learnt by receiving station is very important information.During netinit, can stipulate the details and the out of Memory of son field in the length, control field 59 of control field 59.

For user profile and network control, should in each station, be stored into a certain data transfer rate/connectedness table (RCT) 90-92, and be shown to the user with effective and efficient manner.A kind of like this data transfer rate/information of connectedness table also can be made to supply with program when needs and use.The RCT 90-92 of example is made up of data transfer rate/connectivity state figure among Fig. 9.As shown in Figure 10, RCT can be used for another route that transponder was organized and passed through to user profile, network again.In addition, because initial data rates is known, RCT helps the network throughput that increases.After certain hour, all RCT may need to refresh, because certain S1 station has been adapted to this data transfer rate, some stations are in fact mobile, or have new station to attempt to add in the network.Under the latter event, must carry out another initialize routine.

Demonstrate the example of user network information for station D shown in Figure 10, show that station D can not be received by station B, also promptly concerning the B of station station D represent the terminal of a concealment.In this example, corresponding message of display surface 101 expressions, the position is adjusted in its suggestion.In addition, the display surface 100 of example shows, stands communication restriction between D and the station A on lower data transfer rate.As shown in second display surface 101 of Figure 10, this means that the transmission of 1.6MB file will need finish in 2 minutes.Therefore, demonstrate to user D, suggestion shifts near a little station A.

In high data rate systems, excessive head expense can followingly be avoided like that.The all stations (for example station S4 of beep-pager function) that use in using the subsystem of low data-rate transmission require much lower SNR, therefore, than selected SN (SN=S1) it has much higher antijamming capability (exceeding 20-30dB) to the ripple of making an uproar.Application of repetition coded algorithm and suitable sign synchronization mode can design a RPLH, and it has sufficiently high antijamming capability to low data-rate transmission.Yet the required length of a kind of like this head can reduce the performance of SN and other High Data Rate subsystem significantly.In conjunction with Figure 14, with the example of the such head of explanation, it has the synchronization character that has increased length, with the antijamming capability that should be used for being improved.

From realize research that complexity (price) and efficiency of transmission done with respect to system's antijamming capability, drawn a kind of double mode RPLH scheme.A kind of RPLH of so-called low data rate compact model (L-RPLH), data transfer rate compression (RR) factor height to 8 that it is supported in the SN transmission mode.The RR that the RPLH (H-RPLH) of comparatively expensive high data compression pattern can make SN communication have maximum reaches 64.The SNR that the subsystem that H-RPLH supports is worked, than work under the free of data rate compression (being RR=1) at the SN link and keep the required SNR of acceptable packet success rate, can hang down more than the 20dB.Network in SN (S1) and High Data Rate (S2) transmission mode adopts L-RPLH usually, when just thinking to require in the communication network element low data-rate transmission (S3) and/or distant control function (S4), just excites H-RPLH.Rely on this scheme, and supposition healthy and strong direct carrier wave checking circuit in H-RPLH station works, even then under the situation that head itself can not correctly be decoded, also can be to each the station declaration L-RPLH traffic carrying capacity on the horizon in the H-RPLH scope.Netinit and for the initial channel quality assessment in SN station is all realized in the H-RPLH pattern.

In order to reach high reliability (antijamming capability), by means of the average pulse program preamble that receives is analyzed its periodically composition, can make receiving station determine the pattern (L-RPLH or H-RPLH) of head.(be noted that according to the present invention this is not the main application of preamble.) for example,, can under 0dB, reliable mode detection (for the reliable Detection of data field 51, needing RR is 64) be arranged in that SNR is low with the preamble data flow that receives average 16 times or more times.For example, the preamble pulse train 10001000...... of 8 slot cycles (2 4-PPM symbol lengths), can be used for showing that header pattern is H-RPLH, and also have the preamble pulse train 10000010...... of 8 slot cycles, can show that header pattern is L-RPLH., also can be applied to healthy and strong direct carrier wave and detect middle the detection that a kind of circuit that the head mode detection adopts at receiver end.

For the beginning of definite control field 59 and the beginning of data/subsystem field 51 subsequently, that may be repeated encoding, need frame synchronization.If adopt the PPM code signal to transmit, frame synchronization also is the basis in order to compression PPM character boundary.For this reason, after preamble 52, can transmit a special pulse composition 53 (seeing Fig. 4 A) immediately.Common solution is to adopt illegal PPM symbol (for example every symbol is more than one pulse) to make the synchronization character 53 uniquely can be detected, perhaps by common solution a kind of suitable binary sequence is detected (indicating required correlated characteristic) by a correlator circuit.Yet single the synchronization character 53 that is operated under the H-RPLH condition may become long excessively, requires correspondingly long correlator circuit thereupon.Another problem is that synchronization character 53 must be embedded in the selected PPM form, retrains to defer to the average power that is applied by infrared light supply (duty cycle), and makes the DC level that receives can keep continuity.

Now, in conjunction with Figure 11 a kind of solution is described, it can avoid DC level skew keeping under the duty cycle, and can reduce required correlator length under the H-RPLH condition.Not to adopt long, an independent synchronization character 53, form a suitably long synchronization character but use two relatively shorter synchronization characters.First synchronization character is embedded in the selected PPM sign form in this wise, makes corresponding first correlator 110 also promptly not have the rolling land of making an uproar ideally and produces an output, and it is corresponding to second specific synchronization character.Then, the output of this first correlator 110 after a threshold value operating circuit 113 is added to the output of second correlator 112, has just provided symbol/frame synchronization information as the input of corresponding second correlator 112.This scheme has reduced the hardware spending in the synchronous detecting significantly.In addition, this scheme is compatible mutually with double mode head transmission method (L-RPLH or H-RPLH).

The two-stage type synchronization scenario that the following describes can be expanded, and makes additional information to transmit together with synchronizing information.For example, use second synchronization character (just, such as B in 4 kinds of different modes ₁=+1 ,+1 ,-1 ,+1 ,-1}, B ₂=1 ,+1 ,-1 ,+1 ,+1}, B ₃=1 ,-1 ,+1 ,-1 ,+1}, B ₄=+1 ,-1 ,+1 ,-1 ,-1}), make two different second level correlators can distinguish out the composite sync sequence of 4 kinds of acquisitions (supposition here, every kind of pattern of second synchronization character has the pattern of a complementation).4 kinds of sequences that obtain on first correlator, 110 outputs should have good autocorrelation or cross correlation.This scheme can pass out 2 bit informations together with synchronizing information.Similarly, can promote this scheme, such as comprising that into first synchronization character transmits added bit information.

Below, will further specify the two-stage synchronization scenario possible under the low SNR and the details of symbol/frame synchronization.Figure 11 shows the bright above-mentioned two-stage relevant programme that is used for frame and sign synchronization under low SNR.In this example, first correlator 110 is designed to first synchronization character of binary value is played response.The output of first correlator 110 becomes ternary values (+1,0 ,-1) behind circuit 111, provide as input to second correlator 112.Output by circuit 113, the second correlators 112 becomes binary value (0 ,+1) again, is fed on the memory cell 114 by the time slot clock control of PPM system; Signal on the output 67 { synchronous characteristic position } has been represented synchronizing information.

According to the present invention and corresponding state diagram, provided the another kind of implementation method of receiver among Figure 12 and Figure 13.This receiver has desirable characteristic, and (under medium or high SNR) and healthy and strong (under low SNR) carrier wave measuring ability can be provided fast.As shown in Figure 12, two threshold dectors 121 and 124 are arranged.Threshold dector 124 is applied to Fast carrier and detects, and threshold dector 121 is applied to healthy and strong head detection 123 and Data Detection 122.Healthy and strong head detector 123 provides signal { preamble _ Q-character } to being called the functional block 126 that carrier wave concludes, purpose is to conclude the signal that provided by Fast carrier detector 125 { fast _ carrier wave _ Q-character }.{ fast _ carrier wave _ Q-character } signal provides Fast carrier to the good SNR and detects medium, and { preamble _ Q-character } signal provides slower signal and is used for carrier wave and detects under low SNR.When both combined, two signals { quick _ carrier wave _ Q-character } and { preamble _ Q-character } provided healthy and strong and carrier wave detection fast.Square frame 126 produces signal { carrier wave _ Q-character } (having indicated successful carrier wave detects) from these two signals.When { preamble _ Q-character } not occurring in { quick _ carrier wave _ Q-character } the formation certain hour afterwards, wrong false an alarm is taken place, by signal { quick _ carrier wave _ as to reset } { quick _ carrier wave _ Q-character } (thereby { carrier wave _ Q-character }) resetted.

Healthy and strong head detector 123 provides signal { head _ Q-character, data block _ size, synchronously _ and Q-character, L (pattern) } signal, and provide possible other signal (all fields that depend on transmission in control field 59) to unshowned, other function of receiver.

Because the RR known to the back of the control field 59 during receiving healthy and strong head 50 has indicated channel quality (SNR), thus can use this information together with modulator approach information, during reception data/subsystem field 51 with the threshold value V of comparator 121 _Th2Adjust on the optimum value.(120 feedback N bits from frame 123 to frame.) the threshold value V of comparator 124 _Th1Selected as to have best Fast carrier to detect.

Among Figure 14, example goes out a synchronization character of being made up of two short synchronization characters (sequence 1 and sequence 2).Figure 14 shows bright, and how the PPM transmitter is combined into a long synchronization character according to the present invention with first word (S) and second word (B).Show again in addition this synchronization character is with what kind of order transmission in all symbolic frames of 4-PPM.If propagation channel quality is poor, by two short words form this long synchronization character and similarly synchronization character all be suitable for application.Therefore, this method of symbol/frame synchronization can be well suited for designing healthy and strong head in practice.Even only correctly receiving under the situation of a part of synchronization character, also may reach accurate synchronization (passing through correlation detection).

According to the present invention, the user can be freely in data/subsystem field 51 the transmission ciphered data, still, healthy and strong head 50 never should be encrypted, so that it can both be understood in all stations when the station of any participation receives.Owing to data/subsystem field is seemed it is what kind of is not limited, so this Creative Design thought allows that information transmitted can be encrypted in data/subsystem field 51.

Yet, meaningfully, comprise a son (be similar to and be used in access priority information or the pattern field) in control field 59, it can be used for indicating in encryption mode (encryption is above physical layer usually) with the stay of two nights (receiving station) that data/the subsystem field is gone to of the back of transmission and other possible station.

More generally, people can stipulate " attribute " son field in control field 59, and each station can know that therefrom there be (comprising position and length) in it, will know but the connotation of its content is a subclass of standing.The such attribute son field that comprises in the control field 59 of healthy and strong head 50 is shown bright, healthy and strong head design thought is exactly tolerated the degree of freedom of degree out of the ordinary, mainly be intended to and needn't take into account it, just it can fully be understood, and is special under very poor channel condition.

Below, will touch off the example of different implementation methods of the present invention:

1. according to hardware of the present invention, they for example can comprehensively place on the computer card, this card or can be installed in the computer clamshell, be connected on the computer bus, or (for example being the card of PCMCIA (personal computer memory card international association) (PCMCIA) form) in the slot that provides in the described clamshell is provided.

2. similarly, the emittor/receiver here can be made into independent clamshell formula, and they are connected on the computer.

3. can be incorporated in the ancillary equipment (for example printer) in addition, according to emittor/receiver of the present invention.Under some occasion, the pattern of light weight just can with because common ancillary equipment for example just receives data such as printer.When it is required to print work, generally only be that the feedback information of limited quantity is arrived at a station up.Under this type of situation, only need the healthy and strong physical layer header of transmission and some information in the head control field just enough.

4. this creationary scheme also can realize executive program on the hardware engine of digital signal processor or another kind of special purpose with the microcode form.

Claims

1. between dispatching station and first receiving station and second receiving station, realize the method for wireless light communication, first receiving station can receive the data of using the modulation of first modulator approach, second receiving station can receive the data of using the modulation of second modulator approach, and this wireless light communication method is characterised in that:

A. described dispatching station provides a preamble (52), and it comprises all Frames that form the one-period pulse train with definite cycle, and the content of number of time slot (L) and frame is that described all receiving stations are known in every frame;

F. described dispatching station transfers out a synchronization character (53) of calibrating the uniqueness on the described cycle, and the described all receiving stations of the synchronization character of described uniqueness (53) are known;

G. each of described all receiving stations is asked correlation to the synchronization character of the known described uniqueness of the described pulse train in the described shift register and receiving station, so that receiving station reaches the absolute synchronization with described dispatching station behind the described synchronization character of identification (53);

H. described dispatching station indicates in the control field (59) of predetermined length and structure, be that first or second modulator approach will be used to transmit the data in data/subsystem field (51), make and to support whole receiving stations of relevant modulator approach all waiting for described data.

2. the method for claim 1 is characterized in that, the receiving station that can support different modulator approaches switches to its receiver on the relevant modulator approach that indicates in the described control field (59).

3. the method for claim 1 is characterized in that, or in the described control field (59), or in described data/subsystem field (51), comprise addressee's table of described data.

4. the method for claim 1 is characterized in that, pulse position modulation (PPM) is as the modulator approach of transmission.

5. the method for claim 4 is characterized in that, comprises a data transfer rate packed field (RR in the described control field (59); 54), it indicates to a receiving station, and how each pulse position modulation (PPM) symbol in described data/subsystem field (51) will repeat frequently.

6. the method for claim 1 is characterized in that, comprises the data transfer rate packed field (RR of a suggestion in the described control field (59) ^*55) be used to transmit the data transfer rate bulkfactor (RR of a suggestion ^*), it is used to negotiate a data transfer rate that is suitable for communicating by letter most.

7. the method for claim 6 is characterized in that, the data compression rate factor (RR of described suggestion ^*) determined according to the rule of predesignating that under the error rate of taking into account reality this error rate takes place in dispatching station and all receiving stations communication period.

8. the method for claim 1 is characterized in that, comprises a data block size field (BS in the described control field (59); 56), it indicates in described data/subsystem field (51) number with the data cell of transmission.

9. the method for claim 1 is characterized in that, comprises a pattern field (57) in the described control field (59), and the information of its delivery is used for described receiving station is indicated any modulator approach of application.

10. the method for claim 9 is characterized in that, described modulator approach is following a kind of:

4 time-gap pulsing position modulation (4-PPM),

16 time-gap pulsing position modulation (16-PPM),

The modulator approach of in the IrDA standard, stipulating.

11. whether the method for claim 1 is characterized in that, comprises the information to receiving station's signaling in the described control field (59), will be passed on by described receiving station to inform described data.

12. the method for claim 1, it is characterized in that, described control field comprises such information in (59), it can make arbitrary receiving station do not arrived by addressing, perhaps can not support the modulation scheme pointed out in the described control field (59), be used for determining how long described data will be transmitted, to guarantee keeping quiet in these receiving stations between this transmission period.

13. the method for claim 1 or 4 is characterized in that, each of described all receiving stations is used a kind of algorithm, even when causing having potential error code because of the optical communication that degenerates, still can be used to discern described synchronization character (53).

14. the method for claim 13 is characterized in that, described synchronization character (53) is made up of two synchronization characters, makes that the identification in receiving station can be divided into two stages.

15. the method for claim 1 is characterized in that, is determined the data transfer rate that adopts in the described data of transmission by a receiving station and/or dispatching station.

16. the method for claim 1, it is characterized in that, considering under the current quality of communication channel between dispatching station and the receiving station by a receiving station, determine that the data transfer rate of a suggestion is applied to the transmission of described data, the determining to be based on of the data transfer rate of described suggestion recognized, when control field (59) finishes definitely, and has known when described data/subsystem field (51) begins because known control field (59) thereby when finished definitely.

17. the method for claim 15 or 16 is characterized in that, the formation of the data rate information of described data transfer rate and/or suggestion is available for application program or terminal temperature difference.

18. the method for claim 1 is characterized in that, described control field comprises access priority information in (59), allows the communicator network element that has two coexistences in a communication network element (40) at least.

19. the method for claim 1 is characterized in that, described control field comprises the information of supporting described data encryption in (59).

20. be used for carrying out the transmitter of wireless light communication with first receiving station and second receiving station, first receiving station can receive the data of using the modulation of first modulator approach, second receiving station can receive the data of using the modulation of second modulator approach, and energy of described optical communication applications is by the healthy and strong physical layer header (RPLH of all receiving station's decodings; 50) start, described transmitter comprises:

A., a head generator of preamble (52) is provided, and described preamble (52) is as described healthy and strong physical layer header (RPLH; 50) a part comprises all frames that form the one-period pulse train with definite cycle, and the number of time slot of every frame and the content of frame are that described all receiving stations are known;

B. be used to provide as described healthy and strong physical layer header (RPLH; The device of the synchronization character (53) of the uniqueness that a part 50) and described all receiving stations are known;

C. be used to provide have regular length and known structure, as described healthy and strong physical layer header (RPLH; The device of the control field of a part 50) (59), described control field (59) are indicated in transfer of data the relevant modulator approach that adopts;

E. the device that will be subsequently transmits in the described pulse train of the synchronization character (53) of the described uniqueness of described preamble, synchronization character (53) is calibrated on described pulse train, described control field (59) and described modulated data.

21. the transmitter of claim 20 also comprises the device that described data addressee's table that will transmit is provided, described addressee shows or is given in the described control field (59), perhaps is given in described data/subsystem field (51).

22. the transmitter of claim 20 comprises that also the data transfer rate of suggestion that adopt, that before received in the application data transmission compresses (RR ^*) produce the device of a data field (DSF), and in described control field (59), transfer out and should be used for consulting the data transfer rate compression (RR that itself advises in the data transfer rate that is suitable for communicating by letter most ^*).

23. the transmitter of claim 20 also comprises the device of the number/size that indicates the described data that will transmit.

24. the transmitter of claim 20 also comprises the device that sends signaling to a receiving station, informs whether described data will be passed on by described receiving station.

25. be used for carrying out in multi-modal communications network element and a dispatching station receiver of wireless light communication, described dispatching station transfers out:

A healthy and strong physical layer header (RPLH; 50), it can be by all receiver decodings in the described multi-modal communications network element, and it includes:

Preamble (52), it comprises all frames of forming the one-period pulse train with definite cycle, the number of time slot of every frame and the content of frame are that described receiver is known;

The synchronization character (53) of the uniqueness that described receiver is known;

Control field (59) with regular length and known structure, it indicates in the transfer of data the relevant modulator approach that adopts;

Described receiver comprises:

D. the described pulse train that receives by a shift register is determined the device of clock, the length of shift register is determined by the synchronization character (53) of described uniqueness;

E. the synchronization character of the known described uniqueness of the described pulse train in the described shift register and receiver is asked correlation so that receiver is identifying the synchronization character of described uniqueness (53) reaches absolute synchronization afterwards with described dispatching station device;

F. determine the device whether described receiver can support relevant modulator approach from described control field (59), this modulator approach will adopt in described transfer of data;

26. the receiver of claim 25 also comprises and can make device for switching between a kind of, two kinds or multiple modulator approach.

27. the receiver of claim 25, it is characterized in that, comprise first correlator and second correlator in the described device that reaches absolute synchronization, make use the synchronization character that two synchronization characters produce can be identified in first correlator and second correlator.

28. the receiver of claim 25 also comprises the data transfer rate compression (RR that determines the suggestion of deriving from channel quality assessment ^*) device, the data transfer rate of this suggestion compression (RR ^*) should be used for negotiating the data transfer rate that is suitable for described transfer of data most.

29. the receiver of claim 25 also comprises device, is used for number/size of determining the described data of expection in described control field (59) information transmitted by analyzing.

30. the receiver of claim 25 also comprises device, when the information that receives indicated requirement and transmits, it was used for transmitting described data again.

31. a multi-mode wireless optical communication system comprises: at least one transmitter, this transmitter comprises:

A head generator of preamble (52) is provided, and described preamble (52) is as described healthy and strong physical layer header (RPLH; 50) a part comprises all frames that form the one-period pulse train with definite cycle, and the number of time slot of every frame and the content of frame are that described all receiving stations are known;

Be used to provide as described healthy and strong physical layer header (RPLH; The device of the synchronization character (53) of the uniqueness that a part 50) and described all receiving stations are known;

Be used to provide have regular length and known structure, as described healthy and strong physical layer header (RPLH; The device of the control field of a part 50) (59), described control field (59) are indicated in transfer of data the relevant modulator approach that adopts;

Make the described data that to transmit realize the device of modulation; And

With the device that transmit with the described pulse train of the synchronization character that described uniqueness is arranged (53) back, synchronization character (53) is calibrated on described pulse train, described control field (59) and described modulated data; With

At least one receiver, this receiver comprises:

The described pulse train that receives by a shift register is determined the device of clock, and the length of shift register is determined by the synchronization character (53) of described uniqueness;

Synchronization character to the known described uniqueness of the described pulse train in the described shift register and receiver is asked correlation so that receiver is identifying the synchronization character of described uniqueness (53) reaches absolute synchronization afterwards with described dispatching station device;

Determine described receiver and whether can support the device of relevant modulator approach from described control field (59), this modulator approach will adopt in described transfer of data;

32. the radio optical communication system of claim 31, wherein said at least one optical sender also comprises: the device that described data addressee's table that transmit is provided, described addressee shows or is given in the described control field (59), perhaps is given in described data/subsystem field (51).

33. the radio optical communication system of claim 31, wherein:

Described at least one transmitter also comprises:

Data transfer rate compression (the RR of suggestion that adopt, that before received in the application data transmission ^*) produce the device of a data field (DSF), and in described control field (59), transfer out and should be used for consulting the data transfer rate compression (RR that itself advises in the data transfer rate that is suitable for communicating by letter most ^*); And

Described at least one receiver also comprises:

Determine the data transfer rate compression (RR of the suggestion of from channel quality assessment, deriving ^*) device, the data transfer rate of this suggestion compression (RR ^*) should be used for negotiating the data transfer rate that is suitable for described transfer of data.

34. the radio optical communication system of claim 31, wherein:

Described at least one transmitter also comprises:

Indicate the device of the number/size of the described data that will transmit; And

Described at least one receiver also comprises:

Be used for the device of determining the number/size of the described data of expecting in described control field (59) information transmitted by analyzing.

35. the radio optical communication system of claim 31, wherein:

Described at least one transmitter also comprises:

Send the device of signaling to described at least one receiver, inform whether described data will be passed on by described at least one receiving station; And

Described at least one receiver also comprises:

When indicating, the information that receives is used for transmitting again the device of described data when requirement is transmitted again.